The invention relates generally to quarrying and slag or scrap metal operations, and more specifically to an improved massive body of the type known as a breaker ball or drop hammer, having a rounded top surface for engagement by an electromagnetic lifting crane.
In slag or scrap salvaging or classifying operations, a common procedure is to move large material from one pile to a working area by an electromagnet. The electromagnet picks up the breaker to a height of 10 to 20 feet, or more if needed, power to the magnet is shut off and the breaker is dropped upon the material to be broken as many times as necessary to sufficiently reduce the material to a desired size. The smaller magnetic material is then picked up by the electromagnet and moved to a second pile for other processing. This work cycle is repeated continuously.
A major problem in these operations has been both rapid wear and early failure of the various types of iron and steel drop balls. Many such drop bodies actually wear very little before failing prematurely because of cracks that stem from internal hot tearing characteristics which are prevalent in large heavy metal masses during their manufacture.
The manganese steel breaker bar of U.S. Pat. No. 4,139,237 has exhibited outstanding wear performance and resistance to repeated high impact. That drop hammer has been useful particularly in quarrying operations, for breaking up large masses of rock into smaller pieces, the tool normally being cast with an eye opening at its top for attachment to the chain or cable of a crane. It has not heretofore been adaptable in a practical manner for the slag and scrap processing industry because being nonmagnetic, it required a chain hookup, which was not compatible with the magnet of a scrapyard crane. Repeated changeover from the magnet to the chain and back again was inefficient.
For efficient operation in the scrap or slag industry, handling of the manganese steel breaker bar with an electromagnet was a requirement, tending to indicate the need for a composite design. However, a number of composite-design drop hammers have previously been suggested and experience has shown that under extreme impact forces the fasteners of these previous composite designs yield, causing metal flow and early failures. There are many problems with forming a composite breaker bar or ball, and particularly with a manganese steel body. The metal, a work hardening steel, is virtually impossible to drill and tap for receipt of a threaded fastener. Most connecting arrangements of previously suggested composite drop hammers simply would not work with either the hardness or the shape of the manganese steel breaker bar of U.S. Pat. No. 4,139,237.